Firing mechanism barrier



w. E. THIBODEAU ETAL Jan. 16, 1945.

Patented Jan. 16, 1945 UNITED STATES PATENT OFFICE $67 ,246 FIRING MECHANISM BARRIER 'WilfredIE. Th'ibodeau, Cleveland, Ohio, and Gregory J. 'Kessenich, 'Madison, 'Wi's. Application January 24,1941; Serial No. 375,799

75 claims. 4 (015102-79) I (Granted under the act of March 3, 1883, as amended April'30, 1928; 370 O. G. 757) This invention relates to projectile fuses and in particular to a new form of safety barrier.mem-

her for fuses. H

Broadly the invention consists in providing for the fuse primer a protectivemember of amaterial which is soft-rubber-like in its physical properties, such as resilience and large elastic volume deformation. Any natural or synthetic rubber maybe used or any other product of the general type of polymerizedhydrocarbons having elastic properties similar to rubber. Such a material will undergo tremendous changes in shape or form under the action of centrifugal forceat bullet velocities, and such changes can be utilized to place a fuse in armed condition v This invention bears a general :similarity to that disclosed in applicationSeuNo. 37.5;800 filed January 24, -194 1,'by the same inventors, but differs therefrom in that the rubber-like detent in the present case is-confined at its radial extremities. and hence its useful deformation is both radial and longitudinal.

It is therefore an object of this invention to provide a fuse having a safety member of a material, so-ft-rubber-like in its physical properties which safety member will compress radially and deform longitudinally to arm the fuse under centrifugal force.

To these and other ends, the invention consists in the construction, arrangement and combination of elements described hereinafter and pointed out in the claims forming a part of this specification.

A practical embodiment of the invention is illustrated in the accompanying drawing wherein:

Figure 1 is a sectional view in elevation of the forward portion of a shell, showing the fuse structure;

Figure 2 is a view similar to Figure 1 showing a firing pin freely suspended in the rubber-like medium;

Figure 3 is a view similar to Figure 1 showing radial flanges extending into the rubber-like member;

Figure 4 is a section on the line 44 of Figuse 3;

Figure 5 is a sectional view in elevation of a portion of a fuse showing rod members extending through the rubber-like medium to ensure its rotation;

Figure 6 is a top plan view of Figure 5.

Referring to the drawing by characters of reference there is shown in Figure 1 a projectile I having a cavity 2 in the forward end and a primer 3 inserted at the base thereof. Tightly engaged or tightly and in the latter case the holding ten sion may be regulated -by providing in tube 5 a slot or slot 8 The-lower portion of tube 5 spaced from the walls of cavity 2 for a reason which willpresently appear. 4 Between the lower portion of H] with a central passage H, the latter surrounding the point of the pin 1 I a a The rubber cylinder forms .an effective barrier between the pin and the primer under all ordi nary; circumstances, but under the high rotational velocities-to which projectiles .are subjected, the rubber will compress radially outward, thus enlarging the central passage and unblocking the firingpm,

Since there iisino appreciable volume quantity change in rubber on deformation, space must be allowed in which the deformed rubber can accumulate, and this is provided for in the space between tube 5 and the Walls of cavity 2.

On impact the column of air in tube 5 will be compressed and blow the pin 1 into the primer 3. The frictional holding force of tube 5 or pin 1 will be somewhat overcome by centrifugal force.

It will be understood of course that the head 9 of pin 1 may occupy a considerable portion or all of tube 5 for use as a direct striking member in the case of targets not adapted to set off a fuse by air column actuation.

The space between tube 5 and the projectile. body I need be only so large as to accommodate sufficient rubber to free the head 9 of the pin, and when all available space is filled, expansion of the rubber will cease. The expansion space is of such a length Ah that the central hole will expand to coincide with the diameter D of the tube 5 and form a continuation thereof. This is computed from D hD1 h Ah- D2 quate safety as a barrier, will deform relatively little as compared to a pure gum stock and will have resistance to temperature effects, important in aging. A properly designed detent will withhead Qof .pin fl and the primer is placed a soft rubber cylinder bullets), the radial thickness will be reduced 87%,

the diameter of the central hole increases 520% and the height of the cylinder increases 354%. As stated above, these extreme values can be modified either by compounding the rubber or by mechanically limiting its deformation by proper confinement.

Figure 2 shows a fuse wherein the pin 1 is carried in a central cavity in a rubber cylinder composed of two semi-cylindrical portions. It will be understood that the firing pin in this and other cases may be of any shape, such as spherical, cy lindrical or otherwise and that the expansion space may be located partly below the rubber barrier as well as above it.

Figure 3 shows a fuse generally similar to that of Figure 1, but having the rubber cylinder carried in a casing 15, having radial vanes I6 to reduce the torsional lag in the rubber on sudden rotation.

Figure 5 shows another form of fuse designed to accomplish the results of the vane type of Figure 4. Here, simple upright rods I! are passed through holes IS in the rubber to distribute the rotational impulse. These uprights may be integral with, or fitted into the fuse body.

We claim:

1. In a fuse having inner walls defining a chamber, a firing element and a centrifugal safety blocking member therefor, said member composed of a material suffering sufficient elastic volume deformation under centrifugal action to unblock said element, said member having its outer radial extremities confined by said walls when undeformed, but having at least one longitudinal extremity free for expansion.

2. A fuse comprising a housing having an opening at the forward end, a tubular member fitted in said opening but spaced from the inner walls of said housing, a firing pin in said tubular member, a primer in said housing, spaced from but aligned with said tube, and a barrier member between said primer and the end of the tube having a central passage coincident with the fuse axis, sufficiently small to prevent passage of the firing pin, said barrier member being in contact with the inner wall of the housing and being of a materia1 having elastic properties similar to those of soft rubber, whereby, on rotation the material of the barrier will fiow into the space between the tube and the housing and enlarge its central passage to free the pin.

3. In a fuse, a casing, a firing member and a safety blocking element therefor in said casing, said element substantially filling the cross-section of said casing throughout a portion of the longitudinal extent thereof, and composed of a material sufiering sufficient elastic volume deformation under centrifugal action to unblock said firing member, and means engaging the casing and embedded in said blocking member whereby rotation is imparted to the inner parts of said blocking member without torsional lag.

4. A fuse according to claim 3 wherein said means comprise radial vanes.

5. In a fuse according to claim 3, longitudinal holes in said blocking member, said means comprising rod members extending into said holes.

WILFRED E. THIBODEAU. GREGORY J ..KESSENICH. 

